SOLOMONS ISLAND - A disaster at the Calvert Cliffs nuclear plant in Lusby could lead to thousands of deaths because of congested escape routes and other potential problems, anti-nuclear groups said Thursday.

The charges come as plant owner Constellation Energy has submitted designs to add a new third nuclear reactor to the two 30-year-old reactors at the site, plans that county officials say they strongly support.

"The county is very comfortable" with the expansion, said Linda Vassallo, Calvert County's director of economic development. That expansion is still years away from realization.

But opponents, speaking Thursday near the Thomas Johnson Memorial Bridge, said there are only two major escape routes from the county—the bridge and state Route 2/4. Those routes would turn into bottlenecks in an emergency, as many of the 50,000 people who live within 10 miles of the plant tried to flee.

Even in a normal rush hour, bumper-to-bumper traffic snarls the two-lane Johnson Bridge as people drive to and from St. Mary's County to get to jobs at the Patuxent Naval Air Test Center, said Norma Powers, a 19-year resident of nearby Dowell.

"It would be impossible to get out of here if there was an accident. Getting out on a good day is difficult," she said.

The State recently admitted that a second span to alleviate the congestion is at least nine years away based on the time required to get funding and approvals, do the design, and then actually build it.

The groups also pointed to potential problems with the lack of back-up power for emergency sirens and the possibility that emergency responders might abandon their duties to help their families in a nuclear disaster.

"What we saw with (Hurricane) Katrina in 2005 is people will often tend to personal and family needs before their duties," said Kevin Kamps of the nuclear watchdog group Beyond Nuclear.

He also said that emergency sirens are connected to the local power grid, not the nuclear plant, which generates electricity for other parts of the state. If the power went out, so would the sirens that are supposed to warn neighbors of a nuclear incident, Kamps said.

But Bobby Fenwick, Calvert County's emergency response director, said that while the sirens are not required to have backup power, local officials have other ways to communicate with residents. They would send pre-recorded messages to telephones and police officers would drive along major streets with loudspeakers.

"Regarding our evacuation plans, I have spoken with our public safety office and at this time they have not identified any significant deficiencies," Fenwick said.

Evacuation-time estimates conducted by Constellation Energy in 2000 found it would take no more than 6.5 hours to clear the area, he said.

Vassallo said Calvert Cliffs has an "outstanding safety record," and that Constellation Energy is one of the county's largest employers and the largest source of tax revenue.

But Kamps said combining old reactors with a new one could increase the risk for a serious problem at Calvert Cliffs. Reactors are at high risk for malfunctions when they are very new—because there might be flaws in the design—and very old, he said.

Famous nuclear accidents at Three Mile Island and Chernobyl happened during their "break-in phase," Kamps said.

Scott Burnell, a spokesman for the Nuclear Regulatory Commission, disagreed.

"It's an idea that you can apply to any number of technologically advanced systems," Burnell said. "But it does not apply to nuclear power plants," because of the inspections and regulations imposed on them by the Nuclear Regulatory Commission.